Apparatus of the named kind are in particular used to determine geometrical parameters of workpieces. The workpiece is usually fastened to the base plate using a mechanical mount. The base plate is built as solidly as possible and also serves, in addition to the support of the workpiece, as a reference for a coordinate system. The workpiece has to be mechanically fixed in a sufficient manner so that it does not move relative to the base plate during the measurement. The mechanical mount may not deform the workpiece. The workpiece fastened in the mount is sampled from above for the measurement.
Common coordinate measuring units are as a rule designed for relatively large objects to be measured. They typically have an average measuring range between 200 mm×200 mm×200 mm and 50 mm×500 mm×500 mm. The space requirements for installing a common coordinate measuring unit can accordingly amount to between 1500×1500×1500 mm and 4000×4000×4000 mm. Such large machines can have an overdimensioned effect to the extent that mainly relatively small objects are to be measured, e.g. objects of a size of approximately 10 mm×10 mm×10 mm. There is moreover the problem that with a variety of workpiece shapes to be measured the mechanical mount becomes undesirably complex and/or a plurality of replaceable mounts have to be provided.